Has anyone installed an apron front sink before?

Question:Would you be able to tell me how much the sink and labor costs? We have just bought a new house, and it's begging for a farmhouse apron sink. I just don't know if I can afford it, though.
I checked out the prices of the sinks on ebay (the most reasonable), but now I need to calculate a plumber's labor in installing it.
Currently we have a regular two bowl sink.
Thanks!

Answers:
Also the cabinet face frame and doors need to be changed and the counter top cut and support for the sink added.

Most of which are not a plumbers forte.